If everything is prepaid, how do I know that I will actually get the service I'm paying for?

Rover "holds" the money and the sitter isn't paid until 2 days after the stay ends. If you feel that your pets weren't cared for properly, I believe you can get a refund.

I know it can be hard to leave pets in the care of someone else. Make sure to meet with the sitter beforehand, and listen to your gut. Choose a sitter with good reviews; if she or he does a good job with other dogs, they will with yours as well.

Like Shannon said, although you pay Rover up front for the stay (to ensure funds are available for the sitter), Rover doesn't pay the sitter until 48 hours after the stay is complete; this gives both you and the sitter time to contact Rover to resolve any issues there may be (such as the sitter failing to provide services or the owner failing to pick up the dog at the agreed upon time, thus incurring extra charges).

I always recommend holding a meet and greet with a potential sitter, and you're always welcome to meet multiple sitters before making your selection. Ask whatever questions you need to make yourself comfortable with them. Read their profile in full and look for information in the reviews that mentions what is most important to you. If it says 'verified review' it's from a stay booked through Rover. All reviews are in the order they were left, and the sitter can't censor or edit them. (Rover can elect to remove reviews in extreme cases when they are found to be inaccurate/malicious, but I haven't actually heard of it happening, though I have heard of sitters officially disputing reviews.) You can never be 100% sure, but in my experience most of the sitters on Rover really love dogs and take their business seriously.